Loading...
HomeMy WebLinkAboutRS_TIR_180301_v1DECCIO Engineering Inc. 17217 7th Avenue W. Bothell, WA. 98012 (206) 390-8374 Fax: (425) 741-8214 Avon 2-Lot Short Plat # 18------ Drainage Design Report, O&M Manual & SWPP Report Property Location: 1909 NE 14th Street Renton, WA February 20, 2018 Prepared for: Avon Development Deccio Engineering Inc Page i TABLE OF CONTENTS SECTION 1 PROJECT OVERVIEW o Figure 1: TIR Worksheet o Figure 2: Site Location Map o Figure 3: Existing Site Conditions SECTION 2 CONDITIONS & REQUIREMENTS SUMMARY  City of Renton Requirements SECTION 3 OFF-SITE ANALYSIS  Sensitive Areas Map  Drainage Complaint Map o Figure 4: Upstream and Downstream Flow Map o Figure 5: Downstream System Table SECTION 4 FLOW CONTROL & WATER QUALITY ANALYSIS AND DESIGN o Figure 6: Soils Logs o Figure 7: Developed Conditions Map o Infiltration Requirements o Soil Management Plan SECTION 5 CONVEYANCE SYSTEM ANALYSIS AND DESIGN SECTION 6 SPECIAL REPORTS AND STUDIES SECTION 7 OTHER PERMITS SECTION 8 CSWPPP ANALYSIS AND DESIGN SECTION 9 BONDS, SUMMARIES AND COVENANTS SECTION 10 OPERATIONS AND MAINTENANCE MANUAL  Operations and Maintenance Procedures Targeted Drainage Technical Information Report February 20, 2018 1 | P a g e TIR SECTION 1 PROJECT OVERVIEW Project: Avon Development 2-lot Short Plat Site Information: The proposed project is the construction of a 2-lot short plat. The site is located 1909 NE 14th Street, Renton WA. More generally the site is located within SE ¼ of of the SE ¼ of Section 05, Township 23 North, Range 05 East, W.M., see Figure 2: Vicinity Map. The site is bordered by residential lots on the south, east, and west sides of the site. Pre-developed Site Conditions: The site is 11,960 sf and contains an existing home, driveway, patio and walkway and landscaping with a total existing impervious area of 4,254 sf. The lot slopes from north-east to south-west with all runoff leaving the site along the south-west property line. There are no known sensitive areas on site. The soils report prepared for the site show the site soils to be till and not suitable for infiltration . Please refer to Figure 3: Existing Conditions Map.. Developed Site Conditions: The project will consist of construction of a 2-lot short plat with two single family dwellings and driveways. Half Street frontage improvements in the form of curbs, gutters, sidewalks and landscape strip will be required on NE 14 th Street. Please refer to Figure 7: Developed Conditions Map The total proposed impervious area is 7,412 sf as follows:  Lot 1: 3,082 sf (Roof: 2,465 sf, Patios & Walks: 320 sf, Driveways: 297 sf)  Lot 2: 3,082 sf (Roof: 2,465 sf, Patios & Walks: 320 sf, Driveways: 297 sf)  NE 14th ST: 1,248 sf (Pavement: 728 sf (7’x104’) S-walk: 520 sf) Total Area – Replaced Area = 7,412 sf - 4,254 sf = 3,158 sf of new impervious area. Under Section 1.1.2.1 “Small Site Drainage Review” “Threshold” 1 st Paragraph, since project is under 10,000 sf of total impervious area after January 8, 2001 and under the 5,000 sf of NEW impervious area, it is exempt from detention and therefore qualifies for Small Site Drainage Review. However, since the site is proposing a new storm pipe a “Targeted Drainage Report” is required per Table 1.1.2.A. The project will use the Design Requirement’s under “Appendix C” of the 2017 City of Renton Surface Water Design Manual. Specifically, Section C.1.3.2 for small lots under 22,000 sf Targeted Drainage Technical Information Report February 20, 2018 2 | P a g e Figure 1: TIR Worksheet Targeted Drainage Technical Information Report February 20, 2018 3 | P a g e Figure 1: TIR Worksheet Targeted Drainage Technical Information Report February 20, 2018 4 | P a g e Figure 1: TIR Worksheet Targeted Drainage Technical Information Report February 20, 2018 5 | P a g e Figure 1: TIR Worksheet Targeted Drainage Technical Information Report February 20, 2018 6 | P a g e Figure 1: TIR Worksheet Targeted Drainage Technical Information Report February 20, 2018 7 | P a g e Figure 2: Site Location Map Targeted Drainage Technical Information Report February 20, 2018 8 | P a g e Figure 3: Drainage Basins, Sub-basins and Site Characteristics Targeted Drainage Technical Information Report February 20, 2018 9 | P a g e Figure 3 Con’t: Drainage Basins, Sub-basins and Site Characteristics Targeted Drainage Technical Information Report February 20, 2018 10 | P a g e Figure 4. Soils Memo Targeted Drainage Technical Information Report February 20, 2018 11 | P a g e Targeted Drainage Technical Information Report February 20, 2018 12 | P a g e Targeted Drainage Technical Information Report February 20, 2018 13 | P a g e Targeted Drainage Technical Information Report February 20, 2018 14 | P a g e Targeted Drainage Technical Information Report February 20, 2018 15 | P a g e TIR SECTION 2 CONDITIONS & REQUIREMENTS SUMMARY The City of Renton has adopted the City of Renton 2017 storm water manual which governs the design of stormwater systems to serve this project. The Core and Special Requirements are being met in the following manner: City of Renton 2017 storm water manual Core Requirements: 1. Discharge at the Natural Location Under 1.2.1-2, The surveyed contours show all runoff leaves the site towards the south- west. The drainage design proposes to use BMP’s to address the runoff with the flow leaving the site along the south-west side maintaining the natural discharge location. 2. Off-site Analysis The Level 1 downstream analysis showed that there will be minimal impacts on the downstream conditions, since the site proposes to use small site BMP’s to address all stormwater runoff. 3. Flow Control The site is exempt from flow control and will provide BMP’s as outlined in Appendix C Small Site Drainage requirements. 4. Conveyance System A new 12-inch storm pipe is required on the frontage improvements on NE 14th Street. The flow is minimal since it only picks up 106 feet of the roadway and the on-site improvements . 5. Temporary Erosion & Sediment Control All TESC measures proposed will conform to the 2009 KCSWDM during construction, Refer to Section 9 of this TIR for additional information. The measures shown on the TESC plans include: Clearing limits, sediment control, soil stabilization, BMP’s maintenance and construction sequence 6. Maintenance & Operations Maintenance and Operations manual has been provided. Note that a “Declaration of Covenant” may be required. See Section 10. 7. Financial Guarantees & Liability A completed bond quantity worksheet is not required 8. Water Quality Since new pollution generating impervious surface is less than 5,000 sf, water quality is not required. Refer to Section 4 of this report. Targeted Drainage Technical Information Report February 20, 2018 16 | P a g e City of Renton 2017 storm water manual Special Requirements: 1. Other Adopted Area-Specific Requirements There are no area-specific requirements for this project site. 2. Floodplain/Floodway Delineation A review of the FEMA FIRM panels for the site, shows that the site and area of work is outside any floodplain areas and site does not contain any floodplain/floodway delineations. 3. Flood Protection Facilities There are no flood protection facilities located on or directly adjacent to the site. 4. Source Control This final site does not meet the threshold for source control requirements. 5. Oil Control This final site does not meet the threshold for oil control requirements. Targeted Drainage Technical Information Report February 20, 2018 17 | P a g e City of Renton Conditions FINDINGS/CONCLUSIONS: To be determined TIR SECTION 3 OFF-SITE ANALYSIS TASK 1 – STUDY AREA DEFINITIONS AND MAPS Overview This section of the TIR is a Level 1 Downstream Analysis per the City of Renton 2017 storm water manual Section 2.3. The project will consist of construction of a 2 -lot short plat with two single family dwellings and driveways. Half Street frontage improvements in the form of curbs, gutters, sidewalks and landscape strip will be required on NE 14th Street., see Figure 2: Vicinity Map. The site is bordered by residential lots on the north, south, east, and west sides of the site. Upstream Drainage Analysis / Upstream Contributing Area Based on the site contours, there is no off-site drainage from upstream areas draining onto the site. To the north is NE 14th Street which serves to intercept any off-site runoff from the north. The site itself slopes from north to south-west eliminating any off-site runoff from the east and west sides of the site. Therefore the drainage is limited to the site itself. TASK 2 – RESOURCE REVIEW Adopted Basin Plan The site is located in the East Lake Washington Basin which flows into Puget Sound. Community Plan The site is located in the East Lake Washington Basin Planning Area. Basin Reconnaissance Summary Report We are not aware of a current Basin Reconnaissance Summary Report for this area. Critical Drainage Area The site is not considered to be within a critical drainage area as defined by the 2009 KCSWDM. A review of the DOE “water quality assessment” web site shows that the section of the site discharges into is not on the DOE 303(d) list. Sensitive Area Maps Per City of Renton the site does contain areas of steep slope with a potential for landslide hazard sensitive areas. (See “Sensitive Areas Map”) Targeted Drainage Technical Information Report February 20, 2018 18 | P a g e Soils Survey The soils logs for the site show the site soils to be a till and not suitable for infiltration Wetland / Stream Inventory No known wetlands or streams exist with-in the area of grading. A review of the FEMA FIRM panels for the site, shows that the site and area of work is outside any floodplain areas and site does not contain any floodplain/floodway delineations. Drainage Complaints There appeared to be no drainage complaints downstream of the site.. (See “Drainage Complaints Map”) TASK 3 – FIELD INSPECTION A Level 1 site inspection was performed on November 15, 2017. The weather was overcast with temperatures around 55 degrees. The inspection focused on identifying potential downstream drainage and water quality problems As previously indicated, the site slopes to the south-west with all runoff leaving along the south side of the site TASK 4 – DRAINAGE SYSTEM DESCRIPTION, AND PREDICTED DRAINAGE AND WATER QUALITY PROBLEMS OFFSITE LEVEL ONE DOWNSTREAM ANALYSIS 1. The runoff leaves the property along the south-west side then sheet flows south with: Overland flow for a distance of 800 feet south-west, where it flows into the storm system serving I-405. 2. The I-405 drainage system then flows west through the NE Park Drive and I-405 intersection for a distance of 1,000 feet, then west along the north side of NE Park Drive. 3. It then turns north and flows under Lake Washington Blvd discharging into a stream. 4. This stream flows for a distance of 1,500 feet though Gene Coulon Memorial park before discharging into the south end of Lake Washington. 3,500 feet away The total distance covered is just over 1-mile Note: There was no access to most of the downstream area. These areas were on private property or on I-405 right of way and not accessible to inspection. Basin 1 Predicted Drainage and Water Quality Problems The steep slopes located along the freeway may have erosion issues. However, since most of the Targeted Drainage Technical Information Report February 20, 2018 19 | P a g e downstream including the discharge locations were on private property and not accessible to inspection, no drainage issues could be confirmed. TASK 5 MITIGATION OF EXISTING OR POTENTIAL PROBLEMS The project proposes to use small site BMP’s to address the storm water runoff from the proposed site improvements, thus mitigating any downstream impacts. Figure 5: Upstream Area and Downstream Flow Map Targeted Drainage Technical Information Report February 20, 2018 20 | P a g e Figure 6: Downstream System Table F i g u r e 5 Targeted Drainage Technical Information Report February 20, 2018 21 | P a g e Drainage Complaints Targeted Drainage Technical Information Report February 20, 2018 22 | P a g e Erosion Hazard Map Targeted Drainage Technical Information Report February 20, 2018 23 | P a g e Landslide Hazard Map Targeted Drainage Technical Information Report February 20, 2018 24 | P a g e TIR SECTION 4 FLOW CONTROL & WATER QUALITY ANALYSIS AND DESIGN The project will consist of construction of a 2 -lot short plat with two single family dwellings and driveways. Half Street frontage improvements in the form of curbs, gutters, sidewalks and landscape strip will be required on NE 14th Street. Under Section 1.1.2.1 “Small Site Drainage Review” “Threshold” 1 st Paragraph The project is under 10,000 sf of total impervious area after January 8, 2001 and is under the 5,000 sf of NEW impervious area and is exempt from detention. The total proposed impervious area is 7,412 sf as follows:  Lot 1: 3,082 sf (Roof: 2,465 sf, Patios & Walks: 307 sf, Driveways: 310 sf)  Lot 2: 3,082 sf (Roof: 2,465 sf, Patios & Walks: 307 sf, Driveways: 310 sf)  NE 14th ST: 1,248 sf (Pavement: 728 sf (7’x104’) S-walk: 520 sf) Total Imper Area – Replaced Imperv Area = 7,412 sf - 4,254 sf = 3,158 sf of new impervious area. Per Appendix C Section C.1.3.1, the following BMP’s were reviewed and analyzed for use:  Full Infiltration: The soils were found to not be suitable for infiltration.  Limited Infiltration: The soils were found to not be suitable for infiltration.  Rain Gardens: Not feasible due to site constraints and with NO safe overflow path (overflow would be onto adjacent properties.)  Bioretention: Not feasible due to site constraints and with NO safe overflow (overflow would be onto adjacent properties)  Permeable Pavement: The soils are not suitable for infiltration.  Basic Dispersion: (Splash Locks, Rock Pads, Gravel Filled Trenches, Sheet Flow) Not feasible, the 25-foot flow paths cannot be met.  Reduced Impervious Surface Credit: The amount of impervious area is just enough to allow driveway access and parking.  Native Growth Retention Credit: Not feasible due to the small area of each lot.  Tree reduction Credit: not feasible, the site has no significate trees.  Soil Amendment BMP’s: Will be used on site  Perforated Pipe Connection: Will be used. Targeted Drainage Technical Information Report February 20, 2018 25 | P a g e Due to the site constraints and soils type the only BMP that is feasible is having all downspouts tied into perforated stub outs prior to discharging into the street’s storm drain system The project will use the BMP’s as outlined in the Small Site Drainage Design under “Appendix C” of the City of Renton 2017 storm water manual. Specifically, Section C.1.3.2 for small lots under 22,000 sf Since the total driveway PGIS area is under 5,000 sf, water quality treatment is not required. Water Quality Exemption Since the total PGIS surface is 1,322 sf and under the 5,000 sf threshold, the site is exempt from water quality Targeted Drainage Technical Information Report February 20, 2018 26 | P a g e Figure 7: Developed Conditions Targeted Drainage Technical Information Report February 20, 2018 27 | P a g e TIR SECTION 5 CONVEYANCE SYSTEM ANALYSIS AND DESIGN PIPE CAPACITY: ROADWAY The 12- CPEP pipe from the roadway was sized to handle the runoff from the 100-year storm from both the roadway and site improvements. (See “Pipe Conveyance Charts” at the back of report The pipe will convey the runoff of 6,164 sf of impervious area from the two lots and the half street area and sideway areas of 2,400 sf from NE 14th Street. The total area to be conveyed is 8,544 sf or 0.20 acres. With a 100-yr flow of 0.90 cfs from the SBUH Results. Using D.O.T. Chart 35 "Design Charts For Open Channel Flow": 12" CPEP Pipe Slope: 0.50 % Minimum Slope, Mannings: n = .012 100-Year Dev. Flows: 0.90 cfs Design Flow Capacity Results: 12" Pipe Capacity: = 2.50 cfs (flowing full) > 1.50 cfs required Velocity: = 3.25 fps > 3.00 fps required Therefore the 12" CPEP is adequate. TIR SECTION 6 SPECIAL REPORTS AND STUDIES None Required. TIR SECTION 7 OTHER PERMITS Below is the list of anticipated permits required for this project. Other permits may be required that are not mentioned below. Building Permit – New Single Family Residence Targeted Drainage Technical Information Report February 20, 2018 28 | P a g e TIR SECTION 8 CSWPPP ANALYSIS AND DESIGN For the purposes of this report, several standard erosion control procedures will be utilized by the contractor to minimize the amount of erosion and sedimentation perpetuated by the construction of the site. Furthermore, these techniques are proposed for the Construction Stormwater Pollution Prevention Plan (CSWPPP) and should be reviewed and instituted by the onsite contractor. Some of the measures include filter fabric fence, and standard ground cover practices, A construction sequence will also be used to minimize the impacts of erosion due to construction. ESC Plan Analysis and Design (Part A) 1. At just under 12,000 sf the site is small requiring only minimal ESC measures. The 12- Elements of a Construction CSWPPP listed below, discuss and describe the appropriate ESC measure to be used. 2. Due to the small size of the site, no ESC facilities are proposed. Therefore, no analysis of the site’s ESC facilities was required. The proposed BMPs consist of standard items including: filter fences, construction entrance, CB inlet protection and plastic cover, etc. No sediment traps are proposed. 3. The site is fairly flat and the areas of high erosion are minimal and will be controlled by the filter fence around the perimeter of the site. 4. There were no special reports done for the site. 5. No exceptions or modifications are proposed of the “Erosion and Sedimentation Control Standards” ESC Plan Analysis and Design (Part B) A full SWPP Plan and report will be prepared for the site after preliminary approval is received. THE 12 ELEMENTS OF A CONSTRUCTION CSWPPP 1. Preserve Vegetation/Mark Clearing Limits: The clearing limits are indicated on the plan sheet. Furthermore, clearing and grading will be limited to only areas that need to be disturbed for grading/construction of the road surface to preserve as much natural vegetation as possible. Field marking the clearing limits shall be completed prior to clearing and grubbing activities. BMP's: Preserve Natural Vegetation (VEG) Field Marking Clearing Limits (CL) 2. Establish Construction Access: Access to the construction site shall be limited to the rock construction entrance. The construction entrance shall be extended to provide access to the construction vehicle/equipment staging and employee parking areas. BMP's: Stabilized Construction Entrance (CE) 3. Control of Flow Rates: Storm water detention: No detention is proposed for the site since the increase in volume is minimal 4. Installation of Perimeter Sediment Controls: Sediment control will be provided through a combination of filtration through the surround on-site vegetation, filter fence, straw bails, BMP's: Silt Fence (FF) 5. Soils Stabilization: Temporary and permanent soil stabilization will be provided. Temporary stabilization will be provided through the application of straw and/or plastic sheeting to exposed, worked earth. From October 1 until April 30, no exposed soil may remain exposed and unworked for more than two days; after May 1, no exposed soil may remain exposed and unworked for more than seven days. Targeted Drainage Technical Information Report February 20, 2018 29 | P a g e BMP's: Plastic Sheeting, 6. Slope Protection: Slopes shall be protected from erosion through cover and prevention of concentrated surface runoff flows. BMP's: Plastic Sheeting, 7. Protection of Permanent Drain Inlets and Dust/Mud Control: Inlet protection will be provided for all catch basins. BMP’s: Inlet Protection BMP’s: Street Sweeping and watering of dust areas 8. Stabilization of Channels and Outlets: All channel slopes shall be constructed and protected against erosion in accordance with City of Renton BMP's: None required 9. Pollutant Control: Pollutants shall be controlled as described in the Po tential Pollutants section of this SWPPP. 10. Dewatering Control: De-watering: Interception of the water table is not expected to occur, even if there is an increase in precipitation. However, should ground water flows be encountered, the flows can be directed to on site native vegetation for cleanup. BMP's: Native vegetation (As Required) 11. BMP Maintenance: All BMP's and SWPPP elements shall be inspected daily and maintained as required. 12. Project Management: The project shall be managed in a cooperative effort by the project manager, contractor, engineer, and the county inspector. During the construction process, if unforeseen issues arise that cannot be resolved on site, construction activity (other than SWPPP maintenance) shall be halted and the county inspector and the project engineer are to be contacted and informed of the situation. The Erosion Control Lead TBD Since the project is for residential lots, under SCC 30.63 A.530, (2) the project does not fall under the “High Use Sites” covering commercial or industrial sites. BMP C-151: Concrete Handling (Design and Installation Specifications) Concrete truck chutes, pumps, and internals shall be washed out only into formed areas awaiting installation of concrete or asphalt. Unused concrete remaining in the truck and pump shall be returned to the originating batch plant for recycling. Hand tools including, but not limited to, screeds, shovels, rakes, floats, and trowels shall be washed off only into formed areas awaiting installation of concrete or asphalt. Equipment that cannot be easily moved, such as concrete pavers, shall only be washed in areas that do not directly drain to natural or constructed stormwater conveyances. Washdown from areas such as concrete aggregate driveways shall not drain directly to natural or constructed stormwater conveyances. When no formed areas are available, washwater and leftover product shall be contained in a lined container. Contained concrete shall be disposed of in a manner that does not violate groundwater or surface water quality standards Maintenance Standards: Containers shall be checked for holes in the liner daily during concrete pours and repaired the same day Soil Management Plan for “Post Construction Soil Standard” Targeted Drainage Technical Information Report February 20, 2018 30 | P a g e The top soils will be stockpile on-site and reused per “Implementation Options #4b “Amend existing soil in place per the Post Construction Soil Standard” which requires “Stockpile existing top soils during grading and replace it prior to planting…” In addition, the soils will be required to be tested for organic compliance. See the following requirements. Targeted Drainage Technical Information Report February 20, 2018 31 | P a g e Targeted Drainage Technical Information Report February 20, 2018 32 | P a g e Amend Existing Soils, Purpose and Definition Naturally occurring (undisturbed) soil and vegetation provide important stormwater functions including: water infiltration; nutrient, sediment, and pollutant adsorption; sediment and pollutant biofiltration; water interflow storage and transmission; and pollutant decomposition. These functions are largely lost when development strips away native soil and vegetation and replaces it with minimal topsoil and sod. Not only are these important stormwater functions lost, but such landscapes themselves become pollution- generating pervious surfaces due to increased use of pesticides, fertilizers and other landscaping and household/industrial chemicals, the concentration of pet wastes, and pollutants that accompany roadside litter. Establishing soil quality and depth regains greater stormwater functions in the post development landscape, provides increased treatment of pollutants and sediments that result from development and habitation, and minimizes the need for some landscaping chemicals, thus reducing pollution through prevention. Applications and Limitations Establishing a minimum soil quality and depth is not the same as preservation of naturally occurring soil and vegetation. However, establishing a minimum soil quality and depth will provide improved on-site management of stormwater flow and water quality. Soil organic matter can be attained through numerous materials such as compost, composted woody material, biosolids, and forest product residuals. It is important that the materials used to meet the soil quality and depth BMP be appropriate and beneficial to the plant cover to be established. Likewise, it is important that imported topsoils improve soil conditions and do not have an excessive percent of clay fines. Design Guidelines Soil retention. The duff layer and native topsoil should be retained in an undisturbed state to the maximum extent practicable. In any areas requiring grading remove and stockpile the duff layer and topsoil on site in a designated, controlled area, not adjacent to public resources and critical areas, to be reapplied to other portions of the site where feasible. Soil quality. All areas subject to clearing and grading that have not been covered by impervious surface, incorporated into a drainage facility or engineered as structural fill or slope shall, at project completion, demonstrate the following: I. A topsoil layer with a minimum organic matter content of ten percent dry weight in planting beds, and 5% organic matter content (based on a loss-on-ignition test) in turf areas, and a pH from 6.0 to 8.0 or matching the pH of the original undisturbed soil. The topsoil layer shall have a minimum depth of eight inches except where tree roots limit the depth of incorporation of amendments needed to meet the criteria. Subsoils below the topsoil layer should be scarified at least 4 inches with some incorporation of the upper material to avoid stratified layers, where feasible. 2. Planting beds must be mulched with 2 inches of organic material 3. Quality of compost and other materials used to meet the organic content requirements: a. The organic content for -pre-approved” amendment rates can be met only using compost that meets the definition of -composted materials” in WAC I73-350-220. This code is available online at: http://www.ecy.wa.gov/programs/swfa/facilities/350.html. Compost used in bioretention areas should be stable, mature and derived from yard debris, wood waste, or other organic materials that meet the intent of the organic soil amendment specification. Biosolids and manure composts can be higher in bio-available phosphorus than compost derived from yard or plant waste and therefore Targeted Drainage Technical Information Report February 20, 2018 33 | P a g e are not allowed in bioretention areas due to the possibility of exporting bio-available phosphorus in effluent. The compost must also have an organic matter content of 35% to 65%, and a carbon to nitrogen ratio below 25:I. The carbon to nitrogen ratio may be as high as 35:I for plantings composed entirely of plants native to the Puget Sound Lowlands region. b. Calculated amendment rates may be met through use of composted materials as defined above; or other organic materials amended to meet the carbon to nitrogen ratio requirements, and meeting the contaminant standards of Grade A Compost. The resulting soil should be conducive to the type of vegetation to be established. Implementation Options: The soil quality design guidelines listed above can be met by using one of the methods listed below. I. Leave undisturbed native vegetation and soil, and protect from compaction during construction. 2.Amend disturbed soil according to the following procedures: b. Scarify subsoil to a depth of one foot c. In planting beds, place three inches of compost and till in to an eight-inch depth. d. In turf areas, place two inches of compost and till in to an eight-inch depth. e. Apply two to four inches of arborist wood chip, coarse bark mulch, or compost mulch to planting beds after final planting. Alternatively, disturbed soil can be amended on a site-customized manner so that it meets the soil quality criteria set forth above, as determined by a licensed engineer, geologist, landscape architect, or other person as approved by City of Renton. 3. Stockpile existing topsoil during grading, and replace it prior to planting. Stockpiled topsoil must be amended if needed to meet the organic matter and depth requirements by following the procedures in method (2) above). 4. Import topsoil mix of sufficient organic content and depth to meet the organic matter and depth requirements. 5. More than one method may be used on different portions of the same site. Soil that already meets the depth and organic matter quality standards, and is not compacted, does not need to be amended. Maintenance Soil quality and depth should be established toward the end of construction and once established, should be protected from compaction, such as from large machinery use, and from erosion. Soil should be planted and mulched after installation. Plant debris or its equivalent should be left on the soil surface to replenish organic matter. Targeted Drainage Technical Information Report February 20, 2018 34 | P a g e TIR SECTION 9 BONDS, SUMMARIES AND COVENANTS All the necessary documents listed below will be included in the Full TIR report after preliminary approval is received. These will include:  Bond Quantities,  Flow Control and Water Quality Facility Summary Sheet and Sketch  Declaration of Covenant for Privately Maintained Flow Control and WQ Facilities  Declaration of Covenant for Privately Maintained Flow Control BMPs TIR SECTION 10 OPERATIONS AND MAINTENANCE MANUAL Stormwater System Description The stormwater system for the site is fairly basic and contains the following elements:  12-inch storm pipe  Catch basin The stormwater runoff from the site improvements flows over to street catch basin. Water quality treatment is not a requirement for the site since it is under the 5,000 sf threshold.